It is known that a diamond can be made to conduct electricity by illuminating it with ultra violet light, fast electrons or other atomic particles. A switch based on the principle of illumination with ultra violet light has been proposed by Ho et al. in Optics Communication 46, 202 (1983). This switch apparently works reasonably well for power levels up to about 10 kW. It has been known for many years that current flow between a photoemission cathode and an anode can be controlled by illuminating the cathode with an appropriate laser beam.
What is needed is a switch capable of generating nanosecond pulses in the range of 100 kW and more with sharp rise times.